Gehenna Grey
by ArcticDragon119
Summary: When Satan himself threatens, the exorcists know there is only one option left: they must retrieve the Grey Stone, taken to Gehenna many decades ago.
1. Chapter 1

"Mephisto Pheles."

Mephisto glanced at the man who spoke. He had been aware of him for some time now; he had entered his office several minutes ago.

"Ah, Angel. How nice of you to visit! Please, sit." Angel frowned slightly, not moving, but Mephisto continued. "To what may I owe this surprise? Have some tea?"

Angel shook his head. "This is no time for tea." Mephisto shrugged and began to pour himself some. "Mephisto. Listen to me."

Something about Angel's tone made Mephisto stop. He looked up at Angel's serious face.

"What is it?"

"The Grey Stone."

For a moment they were both still.

Mephisto stared at Angel. "The Grey Stone? What would make you bring up such an old thing?"

Angel's brow furrowed. "You know demonic appearances have been increasing lately."

"Yes."

"We received a report yesterday that Satan himself appeared at a monastery in the far north. Everyone there was killed."

"What?" Mephisto was shocked. "But that hasn't happened since-"

"And this morning," Angel said quietly.

All of Mephisto's joking pretense was gone. "What?"

"This morning he appeared again, thirty miles south of True Cross Headquarters. Mephisto, we have to retrieve the Grey Stone."

"Impossible. You know as well as I do that it's in Gehenna."

"One of our researchers recently found three amulets tucked in a hidden room of the Library."

"No. Where they-"

"Yes," Angel said. "Gehenna Keys."

"So then there is a means of retrieving the Grey Stone."

"Yes, but the requirements to release the Grey Stone from Gehenna's grasp call for the blood of five."

Mephisto said slowly, "We could send Rin."

"What, the demon boy? The son of Satan? He can't be trusted."

"Am I right in saying that this is for the Grigori to decide? And besides," Mephisto smirked, "That's the only option."

Angel's teeth clenched. "Damn you, Mephisto. All right, I'll present this to the Grigori."

"Excellent. But that's still only four."

"Hmm." Angel's eyes shifted away from Mephisto, their gaze distant.

"What are you thinking of?" Mephisto asked him.

"I suppose we could…" Angel's gaze returned to Mephisto. "I must return to Headquarters. I need to discuss something with the Grigori." He turned towards the door.

"Discuss what? Where will we find the fifth?"

"We will inform you of the Grigori's decision," Angel said without turning around. "Be vigilant."

"Angel-"

But he was gone.

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><p>Disclaimer: I obviously don't own Blue Exorcist. If I did, I wouldn't be writing fanfiction, I'd be writing the story line.<p> 


	2. Chapter 2

Having nothing else to do, Reiko Kawaguchi sat on the edge of her bed and shot shadows at the wall.

She held her hand out in front of her, watching the shadows file from their hidden places in the corners of her room and wrap around her hand and wrist in a dark, impenetrable vortex. Then a silent push of will sent them whirling into the wall. They made a low humming noise as they met the demonic iron and slunk away, back to their places. She had worn away the paint from doing this for so long. Three of her walls were white, but this one was grey, and reflected the light from the simple fixture above her head.

She held out her hand again, but the shadows were tired and would not come.

"Come on," she said. She was already feeling bored again. "All you do is sit around all day. You can't be that tired."

_We are exhausted_, they whispered in her mind. _Please let us rest._

"Eh. Whatever." Sighing, she flopped back on the bed, her black hair strewn out around her head, and stared at the shiny grey ceiling, the paint also worn away from months, no, years of assault by her shadows. Angel was always scolding her for using her powers.

"If it bothers you that much," she had said one day in annoyance, "Bring me some white paint and I'll repaint it."

He had scowled at her and said, "It's not the paint I'm angry about. You're infusing your demonic energies into the walls. We'll have to seal off this cell when you are dead."

She had told him that was his problem, that she would be gone and wouldn't care. He had slapped her and denied her food for a day.

"If you'd let me out," she mumbled to herself, "You wouldn't have to worry about the walls." She absentmindedly stroked a shadow which had curled itself on the bed beside her. It purred.

_Someone's coming_, it whispered.

"Who?"

_The Paladin._

"Angel?" She frowned. "It's not dinnertime yet. And it's not a Saturday."

_He is here._ The shadow slithered away as the door clicked and unlocked. It opened to reveal Angel, looking especially grumpy.

"Demon," he said shortly, "Hide your tail and come with me."

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><p>Disclaimer: Nope, still don't own Blue Exorcist or any of its characters.<p> 


	3. Chapter 3

As Angel led her down the halls Reiko gazed around her, wide-eyed, at the tall ceilings and sense of splendor which surrounded her. She had never seen this part of Headquarters before. Even on Saturdays, when she was taken to reinforce the charm sealing her demonic heart to the amulet, she only saw dark, tight hallways. These were brightly lit, majestic. Even the few shadows she passed had a regal air to them.

Angel was a sharp contrast to the beauty of the place. He stormed through the various rooms like a gloomy thunderstorm. What he was so angry about, Reiko didn't know. Did it have something to do with this unexplained tour?

"Where are we going?" she asked tentatively.

To her surprise, Angel answered. "I'm taking you to the Grigori. They wish to see you."

Her eyes widened. The Grigori wanted to see her? What was going on?

Presently they came to a set of huge double doors guarded by two exorcists with guns. Upon seeing Angel, they pulled open the doors, and he strode in, leaving Reiko to follow.

The doors slammed closed behind her, and she flinched. They were in a huge, round room, and seated before her were the Grigori. Her stomach tightened as their gaze fell upon her.

"Is this the demon child?" one of them asked.

"Yes," Angel said, pushing her forward.

"Has she shown any signs of rebellion or anger?"

"…No."

"Then she will go."

"But-" Angel took a step forward.

"Quiet! There is no other option. If she turns on them once in Gehenna, Rin Okumura will destroy her."

Gehenna! She was being sent to the demon world?

"And what if Rin goes berserk?"

"The girl Shiemi can control him, yes?"

Rin. Shiemi. So many names flew around her. What was so important to the exorcists that they were willing to let her out of her room after keeping her there for so long? And they were sending her on a mission – to Gehenna, of all places. Something very big had to be at stake.

"Very well. It is decided. Angel, take her to True Cross Academy right away. Take the amulet and give it to Yukio Okumura. That way she can fight if she is needed."

"Are you sure that's wise?"

"We cannot afford for this to fail. The Grey Stone must be retrieved."

"Yes."

"Now go."

"Yes." Angel turned to her, scowling. "Come with me."

Reiko nodded numbly and followed him out of the room.

* * *

><p>Disclaimer: Blue Exorcist not mine. You know that. Reiko, on the other hand, is my creation! And maybe Angel's eternal grumpiness.<p> 


	4. Chapter 4

Reiko followed Angel through several more hallways, but lost in her thoughts she paid no mind to the beauty of the place.

What was the Grey Stone? Who were Rin and Shiemi? Was she really being sent into Gehenna?

She bumped into Angel. Startled, she looked up.

"Watch it, girl," he growled, pulling a key from his pocket. Inserting it in the door he had stopped before, he said, "Through here is True Cross Academy. Behave." Then he turned the key and opened the door.

It opened to reveal a dim hallway lined with beautiful stained glass. The many shadows here rustled as she stepped through the doorway, Angel close behind.

"It's like a completely different building," she murmured, looking right along the hallway. Dozens of doors lined the walls, each with a stained glass window and a small brass number. She turned back towards the door they had come through. It too had a window. "That's strange. The door looked different on the other side."

"That's because it's a different door," Angel said. "I used a special key on the door at Headquarters to take us here."

"Amazing."

"Don't mock me."

"I'm not!"

"Enough sightseeing," Angel said angrily, grabbing her by the wrist. "Come along." He began to pull her down the hallway.

"Let go of me!" Reiko yelled, wrenching her arm free. Angel stared back at her in alarm. Reiko suddenly realized the shadows surrounding them were coming to her aid, unbidden.

"No! Go away," she said in alarm, waving her hand to ward them off.

_Mistress…_

"I don't need you right now," she told them.

They were still for a second, hen slunk back to their places as if whipped.

Before her, Angel stared at her through slitted eyes. "Control yourself," he said quietly, "Or I'll be forced to exterminate you."

A shiver crept up her spine. "Yes. I'm sorry," she whispered, knowing anything else would be a bad idea.

He watched her for a moment, then turned briskly and walked on. Sighing, she followed, and they walked in silence until they came to a halt next to another door.

"Here," Angel said, opening the door, "Step inside."

* * *

><p>Disclaimer: I don't own Blue Exorcist. I wish I did.<p> 


	5. Chapter 5

Four faces turned to face Reiko as she stepped through the doorway. Sitting in desks at the front of the room were two boys and a girl, while in the back of the room an odd man dressed in a white and pink top hat and a matching cape lounged on top of a desk. He looked up when she entered.

"Hmm? Who is this, I wonder?"

"I'm Reiko Kawa-"

"This is the fifth. She will be going with the others," Angel cut her off as he walked into the room behind her. He looked at one of the boys who sat in the desks. "Yukio Okumura."

The boy looked up. "Yes?"

"I'm under orders to give this to you," Angel said with distaste. He held out something on a chain.

The boy named Yukio took it from him. As it dropped into his palm, Reiko saw with a start that it was a large obsidian stone. She knew without seeing that a crack ran along the edge of the stone. It was the amulet in which her demonic heart was sealed.

She must have gasped, because Yukio glanced at her before asking, "What is it?"

"I'm sure Reiko here can explain later," Angel said. "I'll take my leave now. I don't wish to spend any more time here than I need to." With a last sweeping glance over the room, Angel whirled and left.

Yukio immediately turned to her questioningly. "What is it?" he asked again.

Reiko looked away. "It's-" Suddenly she was worried about what these people might think if they knew she was a demon. Angel has always shown an open hatred of her. What if they were the same?

The man in the back of the room smiled when she hesitated. He stood up, twirling an umbrella she hadn't noticed before, and went to stand in front of her.

"I understand," he said, staring down at her. "You're a demon, aren't you?"

Her stomach turned to ice. She looked down at her feet, avoiding his gaze. "I-"

"And your powers are sealed inside this stone. I see," he said. She looked back up to see him take the stone from Yukio. He examined it, then held it out to her.

"Take it," he said.

Her eyes widened. "But… the Grigori said you were supposed to keep it," she protested, switching her gaze to Yukio. To her surprise, he did not seem angry or scared in any way, just curious. She looked at the other two people in the room. They seemed surprised, but nothing more. There was no disgust. No fear. But why?

"Don't you use this to fight in some way? Where we're going, it'll be important for you to have access to your power," Yukio said.

"Fight with it? Where do you get that idea? How am I supposed to fight with a necklace?" Reiko asked incredulously.

"You don't know how to unseal your powers?"

"No." Reiko looked down at the hunk of obsidian sitting innocently in the man's outstretched palm. "I have to unseal them to fight?"

"How else?"

Reiko said nothing.

"Take it anyways," the man said, tossing it at her. Startled, she caught it. "You may need it for something," he added vaguely as he turned towards the boy and girl who still sat behind them. "Bon, Shiemi, this is…" He stopped and glanced back at her.

"Rekio Kawaguchi," she supplied.

"Yes. She'll be going with you into Gehenna."

There it was again. Gehenna!

"Gehenna, that's what the Grigori said!" Reiko said quickly. "Why in the world-"

"That's what we'd like to know, too," said the boy – Bon. He frowned. "Mephisto wouldn't tell us until we were all together." He had streaked hair and pierced ears. Coupled with the frown, Reiko thought, he must always look angry.

"I don't like to repeat myself," the man said. "Oh, I haven't introduced myself, have I?" He did a mock bow, his umbrella held dramatically out to the side. "Mephisto Pheles, at your service."

"Mephisto…" Reiko hesitated, then went on. "Are we really going to Gehenna? Is that even possible?"

"I'll explain everything once Rin is here," Mephisto said, a little irritated at having to repeat himself after all.

"Where is Rin?" asked the girl, Shiemi. She looked at Reiko and grinned. "He'll be excited to meet you!"

"Huh? Why? Who's Rin?"

Just then the door burst open, making Reiko jump. She turned to see a boy with black hair and blue eyes run in, panting slightly. A covered sword hung over his shoulder, and-

Reiko's eyes widened. For behind the boy curled a black, furry tail.

A demon. She wasn't alone.

"Sorry I'm late," the boy managed to say after a few seconds of wheezing. "I got lost-"

"How did you manage to get lost when you have a key which brings you here from anywhere?" Yukio asked, raising his eyebrows in irritation.

"Well, you see, I went past the cafeteria, the food smelled so good that I didn't think about where I was going, and then I thought I saw you, so I-"

"No, never mind. I don't want to know."

"Huh? Well, okay." He seemed to notice Reiko for the first time. "Wait, who are you?"

"…Reiko Kawaguchi."

He grinned widely. "I'm Rin Okumura. Nice to meet you!"

"Rin!" said Shiemi. "Reiko's going with us."

"Eh? Going where?"

Mephisto smiled craftily. "Gehenna. You all are going into the realm of demons."

"What?" Rin growled, "Are you crazy?"

"It wasn't my idea," Mephisto went on smoothly. "But of course, if the Grigori will it to be done, who am I to question their wisdom?"

"But that's-"

"A very bad idea? Probably. But it's for an important cause." Mephisto smiled. "A quest to save the world! How dramatic! I can't wait to see how this goes."

"What do you mean, to save the world?" Bon demanded. "We're all here now; explain."

"All right. Unfortunately, I must talk quickly. The sooner you all leave, the better. So I'll tell you bluntly: Satan has appeared twice in the last week." He paused, expecting some sort of reaction, but they all were silent, too stunned to speak. Mephisto went on. "Three times the amount of exorcists killed on the Blue Night were killed, along with a dozen normal people who were worshipping at the time."

Bon found his voice first. "Is he looking for a suitable host again?"

"Perhaps. Or maybe he is simply becoming more active, using his power to kill people more efficiently. Perhaps it is both. Who can say? Whatever the case, the Order is in grave danger."

"So you send a few inexperienced exorcists to Gehenna? To stop Satan?"

"Not to stop Satan. He is far too powerful for any of you. No, your mission is to retrieve something, something taken to Gehenna a long time ago."

"And what would that be?" asked Yukio.

I doubt any of you have heard of it. It is called the Grey Stone. It was stolen from the Order hundreds of years ago, and taken to Gehenna. With its power, we could all but chain Satan to Gehenna. There would be no more Blue Nights, no more massacres."

"No more deaths," Bon murmured.

"But how will we find it once we're there?" asked Shiemi, "What does it look like? Where will it be?"

"Good questions." Mephisto pulled something out of his cape and set it on a desk. They all leaned closer to get a better look.

"What is this? A toy?" Rin scoffed. Indeed, when Reiko looked at it, it was a small, wind-up bird. Rin picked it up and tried to turn the key.

"It doesn't even work," she said dubiously, setting it back down. "What is this supposed to be?"

"Of course it doesn't work. It won't function in Assiah, because it's linked to the Grey Stone. Once we're in Gehenna, wind it and it will lead you to the Stone."

"A tracker?" Shiemi picked it up and held it at eye level, then smiled. "It's cute."

"Do you think so? I fashioned it myself," Mephisto said as Shimei slipped the bird into her pocket.

"How will we even get into Gehenna? The only one who can create the Gehenna Gate is Sa-" Bon began to say.

Mephisto waved his hand and turned towards the door. Twirling his umbrella, he said, "You'll find out tomorrow. For now, have some dinner and go to bed. You'll need your rest tomorrow!" With that, he left the room.

No one said anything for a moment. Then Rin spluttered, "Tomorrow? We're leaving _tomorrow_?"

"I don't understand," Shiemi said, "Why us? Why not send someone stronger?"

"Who knows?" Yukio sighed. "I suppose we'll find out tomorrow. For now, let's do as Mephisto says and get some rest while we can."

* * *

><p>Sorry it took so long. I had to rewrite this three times to get it right! Enjoy!<p>

Disclaimer: [See previous disclaimers.]


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